var Singleton = function (name) {
    this.name = name;
    this.instance = null;
};

Singleton.prototype.getName = function () {
    console.log(this.name);
};

Singleton.getInstance = function (name) {
    if(!this.instance){
        this.instance = new Singleton(name);
    }
    return this.instance;
};

var a = Singleton.getInstance('sven1');
var b = Singleton.getInstance('sven2');

console.log(a);
console.log(b);

console.log(a===b);